1. Field of the Invention
This invention relates to a bulb socket plug for a wedge base bulb in a lighting device for a vehicle, and particularly relates to an improved construction of connection terminals insert molded in a bulb socket plug body.
The present application is based on Japanese Patent Application No. Hei. 9-213425, which is incorporated herein by reference.
2. Description of the Related Art
A bulb socket for a wedge base bulb and connection terminals, shown in FIG. 9, are disclosed in Japanese Utility Model Publication No. 3-29898. A socket body 50 includes a bulb insertion portion 51 for receiving the wedge base bulb, and a plug 52 to which a connector is adapted to be connected, the bulb insertion portion 51 and the plug 52 being formed integrally with each other. Two connection terminals 60 are integrally incorporated in the socket body 50 by insert molding, and bulb contact portions 61 of the connection terminals 60 are exposed within the bulb insertion portion 51, and connector contact portions 62 of the connection terminals 60 are exposed within the plug 52.
The connection terminal 60 is formed using a single metal sheet, and includes the bulb contact portion 61 for electrical connection to the bulb, and the connector contact portion 62 for electrical connection to the connector, the bulb contact portion 61 and the connector contact portion 62 being formed integrally with each other. The bulb contact portion 61 includes contact portions 63 which resiliently hold a wedge portion of the bulb, and are electrically connected to lead wires of the bulb, an upstanding wall 64 of a generally channel-shape generally surrounding the contact portions 63, interconnecting portions 63 each interconnecting the associated contact portion 63 and the upstanding wall 64, and abutment piece portions 66 abutted against an inner surface of the upstanding wall 64. FIG. 10 is a cross-sectional view taken along the line X--X of FIG. 9, and FIG. 11 is a partly-broken, side-elevational view of the connection terminal 60.
With the above construction, the connection terminals 60 are insert molded in the socket body 50, with an open portion of the upstanding wall 64 of each terminal closed by an insert of a mold, and therefore a resin material will not flow into a space between the contact portions 63, and the connection terminals 60 can be formed integrally in the socket body 50.
A lower portion 67 of each contact portion 63 of the bulb contact portion 61 of the connection terminal 60 is surrounded by the upstanding wall 64, and is supported by the interconnecting portion 65, connected to the upstanding portion 64, and the abutment piece portion 66 abutted against the inner surface of the upstanding wall, and therefore the contact portions 63 are positively prevented from being deformed or unduly bent away from each other when exchanging the bulb, and therefore the resiliency of the contact portions 63 can be stably maintained for a prolonged period of time.
However, with respect to the connection terminals 60 of the above construction, when the bulb is to be inserted into the space between each pair of contact portions 63 so as to attach the bulb to the bulb socket, the bulb is liable to be erroneously inserted or gougingly inserted into a space disposed at the rear sides of the contact portions 63 as indicated by arrow T in FIG. 11. Therefore, in order to prevent the erroneous insertion and the gouging insertion, there has been proposed a connection terminal 70 of a construction shown in FIG. 12.
The construction of the connection terminal 70, shown in FIG. 12, will be described. Those portions identical to those of the above construction will be designated by identical reference numerals, respectively, and explanation thereof will be omitted. Bent piece portions 69 and 69 are formed respectively at upper ends of opposed bent walls 68 and 68 of a channel-shaped upstanding wall 64 of a bulb contact portion 61, and extend to respectively cover spaces disposed respectively at rear sides of contact portions 63 and 63.
Thus, the bent piece portions 69 and 69 are provided at a bulb insertion opening to respectively cover the spaces disposed respectively at the rear sides of the contact portions 63 and 63, and with this construction, the erroneous insertion and gouging insertion of the bulb into the spaces, disposed respectively at the rear sides of the contact portions 63, are positively prevented.
In the connection terminal 70 of the above construction, the erroneous insertion and gouging insertion of the bulb can be prevented, but when molding a socket body 50, with the connection terminals 70 inserted in the mold, the two bent walls 68 and 68 of the connection terminal 70 are bent and deformed inwardly by the injection pressure of an injected resin.
FIG. 13 is a plan view of the connection terminal of FIG. 12, and the problem that the connection terminal 70 is deformed will be described more specifically. During the molding of the socket body 50, the two bent walls 68 and 68 of the upstanding wall 64 of the connection terminal 70 are subjected respectively to operating forces which act respectively in directions of arrows P because of the injection pressure of the injected resin. Therefore, these bent walls are bent and deformed inwardly as indicated by dots-and-dash lines, which has resulted in problems that the bulb can not be inserted or incompletely contacts the connection terminal, and that the resin flows into the space between the contact portions 63, thus causing the defective molding.